This invention pertains generally to inorganic synthesis and in particular to synthesis of energetic salt mixtures.
Traditional general-purpose explosives comprise trinitrotoluene (TNT), which has several disadvantages. It is a Class-A explosive, requiring special mixing and handling procedures and storage facilities, all accordingly increasing the cost of use. The preparation of this explosive is through nitrate substitution of toluene by a mixed acid consisting of concentrated nitric acid and sulphuric acid. The cost of concentrated nitric acid is moderately expensive and the excess nitric acid in the product destabilizes the explosive and presents corrosion problems. Trinitrotoluene is not water soluble and bomb disposal cannot be done economically by steam or hot water.
A binary mixture of ethylenediamine dinitrate (EDDN) and ammonium nitrate (AN) is water soluble, thereby having several advantages over trinitrotoluene such as safer storage as a non-explosive water solution and cheaper disposal. However, the binary mixture has a high melting point, has stability problems, and is expensive. These disadvantages arise primarily from the method of preparation. A recent attempt to improve the synthesis is disclosed in U.S. Pat. No. 4,353,758 by Irving B. Akst and Mary M. Stinecipher. By this method ammonium nitrate in a stoichiometric excess is mixed with ethylenediamine to form the binary mixture. Low yields and purification difficulties have kept the cost of the binary mixture high.
Recently potassium nitrate has been added to improve the stability of the mixture. The problems associated with the binary mixture remain and the amount of chloride impurities is increased by the additional chloride impurities found in potassium nitrate (KN). If these impurities are not removed, the explosive has serious corrosion problems, and if the impurities are removed the cost of the explosive increases greatly. The present method of making the ternary mixture is to mix solid ethylenediamine nitrate, ammonium nitrate and potassium nitrate. Ethylenediamine dinitrate is not commercially available in large quantities and is expensive. Industrial grade ammonium nitrate and potassium nitrate are too impure to be used without the additional expense of purification. Dry mixing three explosives to form an explosive mixture requires special procedures and precautions, causing the cost of the process to increase significantly. As a result of these difficulties binary or ternary mixtures of ethylenediamine dinitrate, ammonium nitrate and potassium nitrate are not being used instead of trinitrotoluene as general purpose explosives.